High-performance computing systems such as supercomputers and server systems adopt high-speed signal transmission, called interconnect, in data communications between large scale integration (LSI) chips. Related art electrical wiring often fail to satisfy transmission with respect to high performance computing systems due to signal waveform degradation caused by channel transmission losses and crosstalk in broadband and/or long distance interconnects. Hence, development and practical application of an optical interconnect configured to convert electric signals into optical signals once to perform communication via optical wiring have been advanced.
In view of reducing the length of electrical wiring, the optical interconnect may preferably have a structure in which an optical transceiver as a minute photoelectric conversion component is disposed in the immediate proximity of the LSI. A silicon photonics technology has been developed for implementing a micro-optical transceiver in a chip form. Silicon photonics is a technology for forming elements each having an optical control function on a silicon substrate by a CMOS process. Examples of the elements with optical control functions include optical modulators, photodetectors, etc., and thin wire waveguides connecting these elements have already been achieved. Several methods for forming an optical interface on a chip have also been developed in order to connect a thin wire waveguide with an optical fiber serving as an external optical wiring.
As an example of the optical interface, a configuration in which a grating coupler fabricated by silicon photonics technology is disposed at the waveguide end is known in the art. An optical fiber serving as an external optical wiring is held substantially perpendicular to the substrate in accordance with a diffraction angle by a fiber holder and optically connected to the grating coupler (e.g., Patent Document 1 and Patent Document 2).